This invention relates to methods and systems for design and drafting, and more particularly, to such methods and systems which allow automatic creation of dimension indicators for geometric objects.
Computer-aided design and drafting systems typically allow a user to produce drawings and designs faster and with more mathematical precision than is possible by using pen and paper. Instead of pen and paper, users of such systems employ one or more computer input or pointing devices (e.g., keyboard, mouse, light pen, and/or digitizer tablet) to create and store a drawing.
Typical computer-aided design and drafting systems include the input device(s), a central processor, a data storage area or main memory, a fixed or hard disk drive unit, a floppy disk drive unit, a display device, an output device (e.g., a plotter or printer for creating a printout of the drawing), an input/output controller, and a bus which interconnects these components and allows communication therebetween. Programs loaded into the system allow the system to operate and define its capabilities as a computer-aided design and drafting system. The programs can be loaded, for example, by inserting a diskette containing the programs into the floppy drive or by automatic reading of the programs from the hard disk at system power-up.
With a computer-aided design and drafting system, a user can create geometric objects such as circles, arcs, lines, and points. A user also can create more complex objects which include one or more of the aforementioned objects as sub-elements. A variety of other geometric objects also can be created.
A user of a computer-aided design and drafting system often includes dimension indicators in a drawing to identify the dimensions of one or more geometric objects in the drawing. Dimension indicators are markings on the drawing which are associated with the objects to indicate, for example, diameter, radius, length, length of a curved surface, linear separation distance, and angular separation distance. Typical dimension indicators include double-tipped and single-tipped arrows. In most instances, a number (or a number and an alphanumeric symbol) is displayed along with the dimension indicator, the number providing a precise dimensional measurement of the dimensioned object.
In a typical computer-aided design and drafting system, a user must manually perform several steps to select the desired type of dimension indicator and the object to be associated therewith. For example, if a user desires to place a diameter indicator near a circle to identify the diameter of the circle, a user must enter a first command to the system to indicate a desire to enter a dimensioning mode; enter a second command to the system to indicate a desire to display a diameter indicator; enter a third command to select the circle; and then enter a fourth command to indicate where the diameter indicator should be placed with respect to the selected circle.